PSLEThe figure is made up of two rectangles, DELJ and JKGH, and two right-angled isosceles triangles, EFL and GFK. ED = 12 cm, GH = 6 cm and EL =
m cm. DJH and FLKJ are straight lines.
- Find the length of DH in terms of m. Give your answer in the simplest form.
- Find the total area of the figure when m = 14.
(a)
Length LK
= 12 - 6
= 6 cm
Length FL =
m cm (Isosceles triangle)
Length KG
= Length CG
= (
m + 6) cm (Isosceles triangle)
Length DH
=
m +
m + 6
= (2
m + 6) cm
(b)
Area of Rectangle DEJL
= 14 x 12
= 168 cm
2 Length JH
=
m + 6
= 14 + 6
= 20 cm
Area of Rectangle GHJK
= 20 x 6
= 120 cm
2 Area of Triangle EFL
=
12 x 14 x 14
= 98 cm
2 Area of Triangle FGK
=
12 x 20 x 20
= 200 cm
2 Total area of the figure
= 168 + 120 + 98 + 200
= 586 cm
2 Answer(s): (a) (2
m + 6) cm; b) 586 cm
2